Anti-bacterial detergent bar

ABSTRACT

AN IMPROVED ANTI-BACTERIAL DETERGENT BAR IS OBTAINED BY INCORPORATING AN ANTI-BACTERIAL COMPOUND IN THE MIXTURE FROM WHICH THE BAR IS FORMED IN A POTENTIATOR. ANTI-BACTERIAL COMPOUNDS TO WHICH THE IMPROVEMENT CAB BE APPLIED HAVE A MINIMUM INHIBITORY CONCENTRATION AGAINST STAPH. AUREUS OF LESS THAN 5 P.P.M, A SOLUBILITY IN WATER OF LESS THAN 1,000 P.P.M. AT 20*C. AND A MELTING POINT OF AT LEAST 70*C. THE POTENTIATOR IS A SOLVENT CAPABLE OF DISSOLVING AT 25*C. AT LEAST 25% OF ITS OWN WEIGHT OF THE ANTI-BACTERIAL COMPOUND.

United States Patent 3,835,057 ANTI-BACTERIAL DETERGENT BAR Wai Ming Cheng, Ellesmere Port, James Francis Davies, Bromborough, and Brian Anthony Pethica, Altringham, England, assigiors to Lever Brothers Company, New York, N.Y.

No Drawing. Continuation of abandoned application Ser. No. 744,686, July 15, 1968. This application Oct. 6, 1971, Ser. No. 187,207

Int. Cl. Clld 3/48, 9/50 U.S. Cl. 252-107 ABSTRACT OF THE DISCLOSURE 3 Claims This is a continuation of application Ser. No. 744,686, filed July 15, 1968, and now abandoned.

This invention relates to an anti-bacterial detergent bar.

The final stages in the production of a bar usually include a step in which a mixture based on a detergent is worked, usually under conditions of shear. The mixture is then shaped to form the bar, usually by plodding and stamping. Materials which can be present in the final bar in small amounts include perfume, opacifiers, whitening agents, colourants, antioxidants and sequestering agents. When an anti-bacterial bar is to be made, the anti-bacterial compound is usually added with the other additives immediately prior to or during the step in which the mixture is worked. The anti-bacterial compounds normally employed in the manufacture of anti-bacterial bars are solid organic compounds. For an anti-bacterial compound to be suitable for use in a bar it must be compatible with the detergent concerned and have an MIC value (minimum inhibitory concentration) against Staph. aureus of no more than p.p.m. Preferably the anti-bacterial compound should have an MIC value against Staph. aureus of less than 2 p.p.m. and particularly preferably less than 1 p.p.m.

It has now been discovered that the anti-bacterial activity of a bar containing an anti-bacterial compound having certain characteristics defined herein can be enhanced by adding the anti-bacterial compound to the mixture from which the bar is produced in a potentiator as herein defined.

The enhancement can be assessed by measurement of the reduction on the hands of flora which are normally present on the skin. These flora are believed to act on sebaceous and other secretions of the skin, particularly the secretion of the apoorine sweat gland, to produce typical body odour.

The invention is applicable to anti-bacterial compounds that substantially do not dissolve or melt during the working in the final stages of the preparation of the bar. Although in general the solubility of a substance in a deter- 3,835,057 Patented Sept. 10, 1974 ice gent bar does not correlate very well with its solubility in water it has been found that for solid organic antibacterial compounds there is a rough correlation between their solubility in most detergent bars and their solubility in water. In order to avoid undue experimentation it is recommended that it be assumed that if an anti-bacterial compound has a solubility in water at 20 C. of no more than 1,000 p.p.m. it is unlikely to dissolve in a detergent bar and as such the present invention is applicable to the anti-bacterial compound. It will be appreciated that there are exceptions to the above recommendation. These will normally be easily recognized. The maximum temperature normally attained in the final stages of the preparation of a bar is about C. The invention is therefore applicable to such anti-bacterial compounds that have melting points of at least 70 C.; or more particularly to those that have melting points of at least C.

A potentiator for an anti-bacterial compound is herein defined to be a solvent capable of dissolving at 25 C. at least 25% of its own weight of the anti-bacterial compound. A preferred potentiator is a solvent capable of dissolving at 25 C. at least 60% of its own weight of the anti-bacterial compound.

Although potentiators are preferred that are liquids or low-melting solids, substances can be used as solvents for the anti-bacterial compound that do not melt or soften until temperatures above 25 C. When such substances are used, they are heated with the antibacterial compound, for example on a steam bath, until solution is attained and then the mixture is cooled to 25 C. to give a solid solution. The mixture can be examined under a microscope to see whether the anti-bacterial compound has remained in solution: if it has the solvent is to be considered as a potentiator as herein defined.

A feature of the invention is the provision of a solution of a solid, organic anti-bacterial compound in a potentiator as herein defined.

It will be appreciated that, before an anti-bacterial compound is included in a bar, its biological properties and its effect on the properties of the bar will have been studied. Before any potentiator is included in the bar its effect on the properties of the bar and its biological properties will have been studied. The maximum amount of any potentiator that can be included will, like the amount of any particular antibacterial compound, vary from compound to compound. In general it is preferred to include no more than 10% by weight of the potentiator; even more preferably no more than 5% by weight of the potentiator should be included. The properties of the bar that the potentiator can adversely affect include the firmness of the bar, mush formation, lathering properties, colour stability and cracking.

The amount of total anti-bacterial compound in the bar should, in general, be no more than 4% by weight of the bar and preferably no more than 2%. Amounts of anti-bacterial compound as low as 0.05% by weight of the bar are effective.

Preferably the detergent on which the bar is based is soap. The nature of the soap base used to prepare the soap is not important. The soap will preferably be an alkali-metal, water-soluble soap of higher fatty acids with 10 to 18 carbon atoms. The alkali-metal should preferably be sodium. The soap bar will normally contain up to 15% by weight of water, preferably from 5 to 12% and minor amounts of electroylte such as sodium chloride, usually no more than 1%.

Soap bars according to the invention can, for example, I be prepared from fat charges having the following composition (parts by weight):

The invention is particularly effective in anti-bacterial bars containing a minor proportion of superfatting agent. A typical superfatting agent consists of a mixture of higher fatty acids with 10 to 18 carbon atoms; a typical superfatted anti-bacterial bar normally contains between 1 to 20% of such a mixture.

The invention is applicable to an anti-bacterial soap bar containing an anti-bacterial compound and a non soap detergent compound or mixture of non-soap detergent compounds as Well as to an anti-bacterial non-soap detergent bar.

Among the classes of non-soap detergents which can be used in the manufacture of an anti-bacterial bar according to the invention are alkane sulphonates, alkene sulphonates, alkylbenzene sulphonates, alcohol sulphates, alcohol ethoxylate sulphates, monoglyceride sulphates, alkanolamide sulphosuccinates, alkyl sulpho-acetates, carboxylic acid alpha-sulphonates, acyl isothionates, 'acyltaurides, acyl-N-methyl taurides and acylamino methane sulphonates. Particular examples of alcohol sulphates are C to C aliphatic alcohol sulphates containing 75% straight-chain and 25% l-methyl alkyl groups.

The non-soap detergents are normally present at least mainly as their sodium salts although the invention is also applicable to anti-bacterial bars in which the non-soap detergent is present in the form of other alkali-metal, alkaline-earth, ammonium or organic base salts.

Particular examples of non-soap detergent active compounds which can be used in compositions of non-soap detergent toilet bars are those described in US. applications S.N. 618,333, 621,134, 621,150, all of which are now abandoned, 611,206 now Patent No. 3,523,089, and 705,- 022, now abandoned.

Although the mode of action of a potentiator is not fully understood it is believed that the potentiator affects the manner of flocculation and subsequent deposition on the skin of the anti-bacterial compound during washing. It is noticeable that during the personal washing operation although the surface of an anti-bacterial soap bar containing a potentiator remains free, or almost free, of anti-bacterial particles, often a high density of small (e.g. 0.5 to 1 micron or less in dimeter) particles is present in the Wash lather. In some cases it is difficult to detect the particles in the lather because of their size or their optical properties. For instance particles of TCC (3,4,4-trichlorocarbanilide) are more readily detected than those of TBS (3 ,5 ,4'-tribromosalicylanilide) A slightly different mode of action is thought to apply when the potentiator is a substantially hydrophobic solvent. In this case, the solvent may act as a vehicle by which the anti-bacterial compound is deposited on the skin. The hydrophobic solvent is in some cases deposited during the personal washing operation on the skin as fine droplets.

For the potentiator to act successfully it is essential that the amount of potentiator in the bar should be greater than the amount of the potentiator capable of dissolving at 25 C. the amount of anti-bacterial compound it is intended to potentiate. 7

The required amount of the potentiator will vary depending upon the nature of the potentiator. In general there will be no advantage gained by adding more than 8 times by weight the amount of the potentiator capable of dissolving at 25 C. the amount of anti-bacterial com- 75 pound it is intended to potentiate. When more than 8 times by Weight is used there will in some cases be a reduction in the potentiation achieved and there will be a tendency for other properties of the bar, as mentioned above, to be afiected adversely. It is preferred to use less than 4 times by weight the amount of the potentiator capable of dissolving at 25 C. the amount of anti-bacterial compound it is intended to potentiate.

Advantageously, particularly when high levels of the potentiator affect the properties of the bar adversely, only a portion of the anti-bacterial compound in the bar is potentiated. For example, if a bar contains 0.5% of TCC and 0.5% TBS sufficient potentiator can be included in the bar to potentiate just half the amount of total anti-bacterial compounds present. In such a case the bar will contain normal discrete particles of anti-bacterial compound but, in comparison with the bar containing no potentiator, the amount of these particles present will be about half.

When partial potentiation is not involved a particular aspect of the invention is the provision of an anti-bacterial soap, containing an anti-bacterial compound as herein defined in which no particles of the anti-bacterial compound can be detected optically. The invention can provide a transparent anti-bacterial bar; not attainable before with the comparatively insoluble anti-bacterial compounds to which the invention applies.

The amount of the potentiator in the bar, although necessarily greater than the amount required to dissolve at 25 C. the portion of anti-bacterial compound it is required to potentiate, need not be as great when the potentiator is a substantially hydrophobic solvent as when it is a more hydrophilic solvent.

In general when the potentiator is substantially hydrophobic the amount of potentiator in the bar should be from 1.2 to 4 times by weight of the amount of the potentiator capable of dissolving at 25 C. the portion of antibacterial compound it is intended to potentiate.

When the potentiator is a solvent with both hydro philic and hydrophobic properties the amount of the potentiator in the bar should be 2 to 4 times by weight the amount of the potentiator capable of dissolving at 25 C. the portion of anti-bacterial compound it is intended to potentiate.

It is preferred to dissolve the amount of anti-bacterial compound it is intended to potentiate in the potentiator before incorporation of both in the mixture based on a detergent from which mixture the bar is formed by working and shaping.

It is also preferred to ensure that, after the anti-bacterial compound and potentiator have been added to the detergent mixture, the mixture is not worked too hard. In particular it is preferred if the temperature of the detergent after the anti-bacterial compound and potentiator have been added is not allowed to rise above C., particularly preferably not above 35 C.

It is also preferred if the anti-bacterial compound and the potentiator are added at a late stage in the processing of the detergent mixture. Preferably the anti-bacterial compound and the potentiator should be added to the mixture after the mixture has been milled at least once after other additives, such as preservatives and dyestuffs, have been added. Such additives are often added in aqueous solution and it is preferred to avoid contracting the anti-bacterial compound and potentiator unnecei arily with water.

For the above reasons it is also preferred to incorporate the anti-bacterial and potentiator in the detergent substantially at the expense of water that is normally present. This means that the mixture into which the anti-bacterial compound and the potentiator are incorporated is dried more than normally.

Examples of anti-bacterial compounds to which the invention is applicable and that have been used and strongly recommended for use in detergent bars are given in Table I.

TABLE I Minimum inhibitory Melting Solubility at 25 C. inconcentration point, v. Staph; Anti-bacterial compound C. Water Soap aureua, ppm;

3,4,4'-trlchlorocarbanillde 252 Virtually insoluble Substantially insoluble 0. 1-0. 2 3-trifiuoromethyl-4,4-d.ichlorocarbanilide 211-212 do 1 do 0. 2-0. 4 3,5,4-tribromosalicylanilide 1 224-228 sparingly soluble 0.. 3,5,3,4-tetrachlorosalicylanilide 160-162 do 0. 2 3,5,-dibromo-2trifiuoromethyls do 0. 2 2,2-dlhyd.roxy-3,3,5,5,6,6'-hexachlorodiphen 161 0. 6 2,2-dihydroxy-3,3',5,5-tetrachlorodiphenylmethane. 166 2,2-dihydroxy-3,3,dibromo-5,5-dichlorodiphenylmethan 187-188 2,2 -dihydroxy-3,3 ,5,5 -tetrachloro-diphenylsulphide 187-188 2-hydroxy-4,4-dich1orodiphenylether 78-79 2-hydroxy-4,2,4-trichlorodiphenylether. 56 2-hydroxy-3,5,4-tribromodiphenylether 110-112 Tetramethylthiuramdisulphide 149-151 2-mereaptopyridine-N-oxide (Zn complex) Potentiators that are particularly effective includezalkylphosphoramides, such as hexamethylphosphoramide; alkylureas, such as tetramethylurea; mixtures of C to C fatty acids and polyethylene glycols; anionic-cationic complexes formed by mixing, if necessary with warming, amines and acids, preferably organic. The amines can be aliphatic primary, secondary or tertiary amines or aliphatic or alkylaryl quaternary ammonium compounds. The amines should normally include a long-chain fatty group and the total number of carbon atoms in the amine should preferably be at least 10. Preferred acids are straight-chain carboxylic acids. A preferred carboxylic acid is an alkylethoxyacetic acid having the general formula R(OCH CH OCH CO H,

where n is 1 to 25, preferably 1 to 10, and R is a longchain C to C group. The total number of carbon atoms in the cationic and anionic parts of the complex preferably should be at least 10 and less than 40, and even more preferably 10 to 30; phosphine oxides such as trioctylphosphine oxide; amine oxides such as lauryldimethyl amine-N-oxide; and complexes formed from amine oxides and carboxylic acids such as acetic acid; substituted ammoniurn phosphates such as the salt formed between triethanolamine-6-EO and orthoor pyro-phosphoric acid.

Table II gives a list of potentiators together with the solubilities of TCC and TBS in these potentiators.

TABLE 11 Percent solubility at C. of N TCC TBS Polyethyleneglycols polyethyleneglycol 600 (mol wt.) 45 Polyethyleneglycol 1,000 (mol wt.) 45 Polyethyleneglycol mono-esters: Polyethyleneglycol 400 (mol wt.) monolaurate 35 Glycerolalkoxylates:

glycerol 12 (mole) ethoxylate 30 30 glycerol 18 (mole) ethoxylate. 35 35 Tetra-alkylureas: Tetramethylurea 50 .Hexa-alkylphosphoramides: Hexamethylphosphoramide 70 40 Polyalkylpolyphosphoramides: Octamethylpyrophosphoramide 25 60 Amine oxides: Lauryldlmethylamine-N-oxide 45 110 Amine oxide carboxylates:

Lauryldimethylamine-N-oxide acetate 95 Lauryldimethylamine-N-oxide palm kernel carboxylate 25 45 Amine oxide sulphonates: Lauryldimethylamine dodeeylben Pnesnlnhnnata 5 25 Phosphine oxides:

Tri-n-octylphosphine oxide- 100 Trlethanolamine 120 Triethanolamine alkoxylates: Trietha ethoxyl 35 Triethanolamiue ethoxylate complexes: Triethanolamine-6-eth0xylatc acetate 40 95 Triethanolamine-G-ethoxylate plam kernel comp exes:

Triethanolamine-tyethoxylate lactate- 45 55 Triethanolamine-6-ethoxylate succinat 35 80 Triethanolamine-fi-ethoxylate citrate 45 Triethanolamine-G-ethoxylate benzoat 25 5 65 55 35 Triethanolamine ethoxylate sulphonates Triet nolaminefi-ethoxylate dodecylbenzene sulphonate- 45 25 Mono-alkylannne complexes: ctylamine palm kernel carboxylate 35 TABLE II.Continued Percent solubility at 25 C. of-

TCC TBS Mono-alkylamine ethoxylate complexes:

Stearyl anline-lO-ethoxylate lactate 55 75 Stearyl amine-10-ethoxylate succinat 45 75 Stearyl amine10-ethoxylate citrate 55 70 Stearyl amine-IO-ethoxylate benzoate 45 Stearyl aminel0-ethoxylate phthalate 45 55 Stearyl amine-10-ethoxylate terephthalate. 45 35 di-Alkylamine complexes: Dicoconutamlne kernel carboxylate 55 Tri-alkylarnine complexes:

Oetyldirncthylamine acetate Cetvldimethylamine palm ker C etyldimethylamine stearate. Cctvldimcthylamine oleate. C ctyldimethylamine glycola C etyldimethylamine lactate- Cctyldimethylamine succinate Cetyldimethylamine citrate. Cetyldimethylarnine benzoate Cotyldimethylamine phthalat Cetvldirnethylamine terephthalat Tri-alkylamine sulphonates: Oetyldimethyla dodecylbenzene sulphonate 45 35 Polvalkylenepolyamines: Polyethyleneimine 6 110 Polyalkylenepolyamine alkoxylates:

Diethylenetriamine-S-propoxylate 175 Diethylenetriamine-20-propoxylat 175 175 Quaternary ammonium alkane complexe Cetyltrimethylarmnonium soap. 45 25 Cetylbenzyldimethylammonium soap* 40 35 *Soap base: 80 tallow, 15 coconut fat, 5 sperm oil distillate.

Table III lists a number of suitable anionic moieties for anionic-cationic complexes.

The potentiating effect can be measured by means of Finger Imprint Tests and Handwashing Tests described possible to screen a number of possible potentiators. It 10 will be appreciated that before a potentiator/anti-bacterial compound system can be recommended for use, biological clearance must be obtained and Handwashing Tests made.

8 washing of the hands with soap solutions containing anti bacterial, subjects washed the hands with test soapbars containing anti-bacterial with and without potentiator. Also, the scale of evaluation of the high level of anti-bacterial or anti-bacterial mixture was efiectively expanded by use of a larger volume of media and inoculum than that described by Vinson, and in addition plates were prepared as described by Vinson, but in which E. coli Was substituted for Staph. aureus.

Table IV gives results for Finger Imprint Tests in soap bars formed from a fat charge comprising 80 parts by weight tallow, 15 coconut oil and 5 sperm oil distillate.

TABLE IV Finger imprint v.

Soap bar TBS TCC TFO" Potentiator Percent Staph. a. E. coli A PE Gm monolaurate 3 D 0 B 2 1. 2 0 2. 5 0

0 5 PEGmim 4 is 6 0 5 PEG L 5 0 5 PE G400 monolaurate 4 3. 7 1. 6

1.4 0 PE Gm monolaurate 4 3. 1 0. 5

0. 5 1. 5 0 1. 0 0. 5 Cetyldimethylammozfium acetate. 5 2. 7 1. 1

'3-triflu0romethyl-4,4-dichl0r0carbanilide. PE G monolam'ate is the monolaurate of a polyethyleneglycol with an average molecular weight of 400.

Finger Imprint Test The Finger Imprint Test used was a modification of the One surprising and significant effect is the effect of potentiated anti-bacterial compounds on E. cOIi, a gramof L. I. Vinson et al., J. Pharm. Sci., 1961, 50, (i0), 827, 45 negative Organism- In Vitro Tests for Measuring Anti-bacterial Activity of Toilet Soap and Detergent Barsz instead of simulated Tables V and VI give the results from two further series of tests using smaller volumes of media and inoculum.

TABLE V Soap bar Potentiator'(2%) gnu. Hexgdecyldimethylamine phthalate TOO TBS TFO F J g..-" Trieghanolamine ethyleneon'de lactate 0. 5

I (1%.-- Triethanolemine ethyleneoxide phthalate 0. 5

L iTL n Triethanolamine ethyleneoxide phosphate..."

do (151..-. Stearylamine 1O ethyleneoxide lactate R S Stearyl lo-ethyleneoxide sulphate T Steagylamine lfl-ethyleneoin'de mulnh e V- Hexamethylphosphoramide W do X do Y-.. Tri-g-oetyl phosphine oxide A fin 7 AB Dimethylfurmamide 0. 5 AC.-- Diethyleneh'lamine 5 propylenenxirln 0 5 TABLE VI Finger imprint Soap v. Staph. bar Potentiator (2%) TCC TBS TFO aureua A 1 0. 6 B 1 3. C 1 1. 7 D-. Dimethyliormamide 0.5 3. 7 E do 0.5 2. 9 F Dimethylenetrlamlne propyleneoxide 0. 5 3. 3 G -.do.--..-, 0.5 2.8 H Methyl fatty imidazoline ether propionate 0. 5 3. 6 T secoriidary Ciralcohol 12 ethyleneoxide. 2 5

O i Dicolconutamine palm kernel acid carboxylate.

2 o L--." Hexadecyldimethylamine laurylethoxyaeetic 0. 5 1. 6

. acid oarboxylate.

M Hexadecyldimethylamlne laurylethoxyacetic 0. 5 3. 6

' acid carboxylate.

N .-do 0. 5 2. 7

0...-. Hexadeeyldimethylamine/tiiethanolamine 0. 5 0. 9

ethyleneoxide/succinic acid carboxylate.

do 0. 5 2. 2 R do 0. 5 2. 8 S--. Lauryldimethylamine ride 0. 5 1. 1 '1 do 0. 5 1. 8 U do 0. 5 2. 7 V Lauryldimethylamine oxide/acetate 0. 5 1. 1 W do 0. 5 1. 8 X do 0. 5 1. 4 Y. Benzyltriethanolammonium ethyleneoxide 0. 5 0. 9

chloride. Z. do 0.5 2. 4 AA .-do 0. 5 1. 9

Handwashing Test The method used has been described by B. M. Gibbs and L. W. Stuttard, J. Appl. Bact., 30, (1), 1967, Evaluation of Anti-bacterial Soap.

A panel of subjects were given control (free of antibacterial agent) soap for regular use, one week before the test began. They were then given either a control soap or a soap containing an anti-bacterial compound with or without potentiator, according to a statistically randomised design. During the test period, the subjects used only the prescribed soaps both at work and at home, and washed their hands with the prescribed soaps at least 3 times a day. On the sixth and seventh days, the resident flora of their hands were evaluated in the laboratory by the method described below. The soaps were then collected and the second weeks soaps distributed, according to the statistical arrangement (when soaps contained 1.0% anti-bacterial, the test weeks were separated by a week in which subjects used only control soap-this pre- TCC, percent Soap bar vented residual elfects). The bacteria on the hands of the subjects were again evaluated on the sixth and seventh days, and the third weeks soap issued, etc. The test continued in this way for 4 weeks.

For the laboratory evaluations, each subject made 4 consecutive washes with control soap, the first three up to the elbows, whereas in the fourth, the hands and wrists only were included. Fifteen seconds soaping, seconds lathering and 15 seconds rinsing were used in each case. This fourth wash Was done in a bowl containing 2 litres of sterile water. The bacteria in each millilitre of water were counted on yeastrel-glucose agar using the poured plate technique and diluting the samples in sterile 0.1% peptone water when necessary (usually 1:10 gave a countable number of colonies). After incubation at 37 C. for 48 hours the number of colonies was counted and the count per bowl determined. For each subject, the mean of the counts on the two days was taken as subjects count for the week. This is considered to be proportional to the number of bacteria constituting the flora.

TABLE VII Reduction in skin flora, log counts per 0.1 m1. wash liquor Potentiator, percent Coconut monoethanolarnide 4-5 ethoxylate Mono-n-butyl di-2-hydroxyethy1ether 59 99 ooooo 25 :5-}Po1yethyleneglyc0l 1,000 26 --{"'6:5.. -Tf.}----" TABLE VIIContinued Reduction in skin flora,

log counts TOO, per 0.1 m1. Soap bar percent Potentiator, percent wash liquor 0.5 1. 45410 1. 23306 0.5 Coconut diethanolamide 25 ethoxylate 4 1. 22588 0.5 Polyethyleneglycol 1,000 (mol wt.) 1. 18959 1. 0 1. 27627 1. 0 Polyethyleneglycol 400 monolaurate 7. 4 0 93134 What is claimed is:

1. In a process for preparing an anti-bacterial soap bar in which process from 0.05 percent to 4 percent, by weight of the bar, of a saop compatible anti-bacterial compound, having a minimum inhibitory concentration against Staph. aureus of less than 5 p.p. m., a solubility in water of less than 1,000 ppm. at 25 C. and a melting point of at least 70 C. and selected from the group consisting of 3,4,4-trichiorocarbani1ide, 3-trifluoromethyl- 4,4 dichlorocarbanilide, 3,5,4 tribromosalicylanilide, 3,5,3',4' tetrachlorosalicylancilide, 3,5, dibromo-2'-trifluoromethylsalicylanilide and combinations thereof, is added to soap and the soap is worked and shaped. to form the soap bar; the improvement, by which the antibacterial effect is enhanced, being that the anti-bacterial compound is added to the soap with a solvent having hydrophobic and hydrophilic properties compatible with the bar and capable of dissolving at 35 C. at least 25 percent of its own weight of the anti-bacterial compounds, the amount of the solvent in the bar being by weight from 2 to 4 times the minimum amount of the solvent required to dissolve the anti-bacterial compound and being more than 0.05 percent and no more than percent by Weight of the bar.

2. A process according to Claim 1 in'which a mixture of C to C fatty acids is added to form from 1 percent to 20 percent by weight of the bar.

3. A soap bar prepared in accordance with the process of Claim 1.

References Cited UNITED STATES PATENTS 3,043,778 7/1962 Kelly .5. 252 -107 3,152,039 10/1964 Matt-son 252-107 X 3,179,596 4/1965 Farrar et al. 252 3,226,329 12/1965 MAcMillan 252-107 3,431,207 3/1969 Russell 252106 3,485,919 12/1969 Markgraf et al 424322 3,594,322 7/1971 Wilson 252106 FOREIGN PATENTS 1,013,040 8/1957 Germany.

OTHER REFERENCES TCC, Monsanto Technical Bulletin No. PC-4A, pp. 1, 6, 11, 19 and 20.

Linfield et a1., Performance of Germicidal and Decdorant Soaps, JAOCS, vol. 37, May 1960, pp. 251-254.

LEON D. ROSDOL, Primary Examiner P. F. WILLIS, Assistant Examiner US. Cl. X.R. 252106 wmrzas @AIENT @EFFHCE CERIEEIQAEE @QRREQMQN Patent No. 1 I Dated Sggtember 10 1 9 24 ai Ming Cheng James Francis Davies and rian Anthony Pethica It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

%nventor(s) W Column 11, line 29 (Claim 1), change "35C." te --25c.--

Signed and sealed this 18th day ef February 3975.

(SEAL) Attest:

I v C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks :ORM powso (wss) uscoMM-Dc 60376-P69 U.5. GOYERNMENT PRINTING OFFICE: I969 0-366-334 

